The Role of Prey in Controlling Expression of a Trophic Polymorphism in Ambystoma tigrinum nebulosum

1994 ◽  
Vol 8 (2) ◽  
pp. 151 ◽  
Author(s):  
M. L. G. Loeb ◽  
J. P. Collins ◽  
T. J. Maret
Keyword(s):  
Ambystoma Tigrinum ◽  
Trophic Polymorphism ◽  
Ambystoma Tigrinum Nebulosum

Kinematic and Electromyographic Analysis of the functional role of the body axis during Terrestrial and Aquatic Locomotion in the Salamander Ambystoma Tigrinum

1992 ◽  
Vol 162 (1) ◽  
pp. 107-130 ◽  
Author(s):  
LARRY M. FROLICH ◽  
ANDREW A. BIEWENER
Keyword(s):  
Muscle Activity ◽  
Functional Role ◽  
The Body ◽  
Ambystoma Tigrinum ◽  
Terrestrial Locomotion ◽  
Aquatic Locomotion ◽  
Wave Patterns ◽  
Axial Morphology ◽  
Electromyographic Analysis

Aquatic neotenic and terrestrial metamorphosed salamanders {Ambystoma tigrinum) were videotaped simultaneously with electromyographic (EMG) recording from five epaxial myotomes along the animal's trunk during swimming in a flow tank and trotting on a treadmill to investigate axial function during aquatic and terrestrial locomotion. Neotenic and metamorphosed individuals swim using very similar axial wave patterns, despite significant differences in axial morphology. During swimming, both forms exhibit traveling waves of axial flexion and muscle activity, with an increasing EMG-mechanical delay as these waves travel down the trunk. In contrast to swimming, during trotting metamorphosed individuals exhibit a standing wave of axial flexion produced by synchronous activation of ipsilateral epaxial myotomes along the trunk. Thus, metamorphosed individuals employ two distinct axial motor programs -- one used during swimming and one used during trotting. The transition from a traveling axial wave during swimming to a standing axial wave during trotting in A. tigrinum may be an appropriate analogy for similar transitions in axial locomotor function during theoriginal evolution of terrestriality in early tetrapods.

A model of inter-cohort cannibalism and paedomorphosis in Arizona Tiger Salamanders, Ambystoma tigrinum nebulosum

2016 ◽  
Vol 09 (02) ◽  
pp. 1650030
Author(s):  
Maeve L. McCarthy ◽  
Howard H. Whiteman
Keyword(s):  
Periodic Solutions ◽  
Structured Populations ◽  
Unstable Equilibrium ◽  
Ambystoma Tigrinum ◽  
General Applicability ◽  
Previous Theory ◽  
Tiger Salamanders ◽  
Stable Equilibria ◽  
Per Capita ◽  
Ambystoma Tigrinum Nebulosum

Cannibalism is widespread in size-structured populations. If cannibals and victims are in different life stages, dominant cohorts of cannibals can regulate recruitment. Arizona Tiger Salamanders, Ambystoma tigrinum nebulosum, exhibit facultative paedomorphosis in which salamander larvae either metamorphose into terrestrial adults or become sexually mature while still in their larval form. Although many salamanders exhibit cannibalism of larvae, the Arizona Tiger Salamander also exhibits cannibalism of young by the aquatic adults. We formulate a differential equations model of this system under the assumption that the terrestrial adults do not impact the system beyond their contribution to the birth of young larvae. We establish non-negativity, boundedness and persistence of the salamander population under certain assumptions. We consider the equilibrium states of the system in the presence or absence of a birth contribution from the terrestrial or metamorph adults. Constant per capita paedomorphosis leads to asymptotically stable equilibria. The per capita paedomorphosis rate of the larvae must be density dependent in order for periodic solutions to exist. Furthermore, the stage transition rate must be sufficiently decreasing in order to guarantee the existence of an unstable equilibrium. Periodic solutions are only possible in the presence of a unique nontrivial unstable equilibrium. Our results conform to previous theory on paedomorphosis which suggests general applicability of our results to similar systems.

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